Plunger lift assembly

ABSTRACT

The present application includes a plunger assembly having an internally coupled clutch assembly within a cage. The clutch retainer assembly is free from direct impact with objects at the bottom of the well that may cause damage to the clutch assembly. The clutch assembly includes a multi-piece clutch to contact a stem within the cage. One or more retainers are used to maintain the orientation and alignment of the clutch within the cage. The cage includes a linear taper to increase wall thicknesses and further includes one or more flow cuts along the exterior surface of the wall to increase the volume of fluid that can enter through the one or more ports in the cage.

BACKGROUND

1. Field of the Invention

The present invention relates generally to oil field tools, and more particularly to an improved plunger lift assembly.

2. Description of Related Art

The oil and gas industry has been drilling and completing wells to produce hydrocarbons for decades. Plungers are downhole tools used by operators to remove liquids and contaminants from productive natural gas wells. A plunger acts as an artificial lift. In operation the plunger passes down through the well until it reaches a contact point in which the plunger seals shut. Pressure beneath the plunger builds and raises the plunger in the well, thereby removing all the liquids above the plunger.

A number of disadvantages exist with plungers. Bypass valve style plungers may have an external clutch retainer. The clutch retainer usually coupled directly to the cage. The cage and clutch retainer are located at the lower end of the plunger and experience great impact forces at the bottom of the well. The valve cage is typically thin-walled and susceptible breakage from the impact forces. Additionally, the clutch retainer being located externally, experiences direct impact forces at the bottom of the well and can be another failure point. When failed, pieces of the clutch and damaged retainer break from the plunger in the well, requiring each piece to be fished out, thereby increasing costs to the operator. Another disadvantage of bypass valve style plungers is the clutch. Clutches may typically be two-piece assemblies and use a spring wire or elastomeric bands to apply pressure.

An improved plunger assembly design is needed. Although great strides have been made, considerable shortcomings remain.

DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the application are set forth in the appended claims. However, the application itself, as well as a preferred mode of use, and further objectives and advantages thereof, will best be understood by reference to the following detailed description when read in conjunction with the accompanying drawings, wherein:

FIG. 1 is an exploded perspective view of a plunger assembly according to the preferred embodiment of the present application

FIG. 2 is an enlarged side section view of a portion of the plunger assembly of FIG. 1;

FIGS. 3 and 4 are enlarged side section views illustrating a stem used in the plunger lift assembly of FIG. 1 in two different positions;

FIGS. 5-8 are associated views of an internal clutch assembly used in the plunger lift assembly of FIG. 1;

FIGS. 9-10 are associated views of a clutch retainer used in the plunger lift assembly of FIG. 1;

FIGS. 11-12 are associated views of a cage used in the plunger lift assembly of FIG. 1; and

FIG. 13 is a bottom view of the cage of FIG. 12 showing exemplary flow cut designs.

While the system and method of the present application is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the application to the particular embodiment disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the process of the present application.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Illustrative embodiments of the preferred embodiment are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

In the specification, reference may be made to the spatial relationships between various components and to the spatial orientation of various aspects of components as the devices are depicted in the attached drawings. However, as will be recognized by those skilled in the art after a complete reading of the present application, the devices, members, apparatuses, etc. described herein may be positioned in other desired orientations. Thus, the use of terms to describe a spatial relationship between various components or to describe the spatial orientation of aspects of such components should be understood to describe a relative relationship between the components or a spatial orientation of aspects of such components, respectively, as the device described herein may be oriented in other desired directions.

The system and method in accordance with the present application overcomes one or more of the above-discussed problems commonly associated with existing plunger assembly designs. Specifically, the system of the present application is configured to incorporate an internal clutch retainer, 3-piece clutch, and improved cage. The cage is configured to assist in the passage of liquids, hydrocarbons, and solids; and prevent premature wear and breakage typically associated from impact forces. These and other unique features of the system are discussed below and illustrated in the accompanying drawings.

The assembly will be understood, both as to its structure and operation, from the accompanying drawings, taken in conjunction with the accompanying description. Several embodiments of the assembly may be presented herein. It should be understood that various components, parts, and features of the different embodiments may be combined together and/or interchanged with one another, all of which are within the scope of the present application, even though not all variations and particular embodiments are shown in the drawings. It should also be understood that the mixing and matching of features, elements, and/or functions between various embodiments is expressly contemplated herein so that one of ordinary skill in the art would appreciate from this disclosure that the features, elements, and/or functions of one embodiment may be incorporated into another embodiment as appropriate, unless otherwise described.

The system of the present application is configured to translate within an oil/gas well. The plunger lift assembly is configured to translate up and down through a well by selectively permitting the passage of hydrocarbons, contaminants, and liquids through an internal chamber. At the bottom of the well, the plunger assembly is configured to impact a stop or bumper. The impact forces are transferred through a cage to the body. The plunger assembly includes the cage surrounding an internal clutch, a clutch retainer, and a stem. The stem extends from a lower end of the cage during the fall through the well. In this orientation, hydrocarbons, liquids and contaminants are configured to pass around the stem and through channels in the cage into the internal chamber of a mandrel. This passage of fluid permits the plunger to fall through contaminants and liquid in the well. Upon contact at the designated location, the orientation of the stem changes within the cage. The stem presses up within the cage and contacts a bottom portion of the mandrel, thereby forming a seal and preventing the future passage of liquid and contaminants through the internal chamber. In this sealed condition, pressure builds up beneath the plunger which eventually reaches a level where the pressure lifts the plunger to the surface. At the same time, the liquid and contaminants above the plunger are also brought to the surface. The stem is unseated upon contact with the surface of the well.

Referring now to the figures wherein like reference characters identify corresponding or similar elements in form and function throughout the several views. The following Figures describe assembly/system 101 and its associated features.

Referring now to FIG. 1 in the drawings, an exploded perspective view of plunger assembly 101 is illustrated. Assembly 101 includes a mandrel 103, stem 105, clutch assembly 107, clutch retainer 109, and cage 111. Cage 111 is configured to couple to an end of mandrel 103 in a threaded relationship. Cage 111 and mandrel 103 are detachable. When coupled, cage 111 and mandrel 103 form the body of assembly 101. Stem 105 is configured to translate within cage 111 between at least two positions, outside of mandrel 103. Stem 105 is configured to selectively regulate the flow of working fluid through mandrel 103 by changing its position within cage 111. Clutch assembly 107 is internally located within cage 111 along with stem 105. Clutch assembly 107 is configured to engage a portion of stem 105 while in both the first position and the second position. Each part is described in further detail in the following figures.

FIG. 2 illustrates a partial side section view of the individual parts of assembly 101. From FIG. 2, an internal view of cage 111 is more clearly seen. When assembled, each part is located as illustrated in FIGS. 3 and 4. In particular, the two positions of stem 105 are illustrated in FIGS. 3 and 4. Also of note is the particular location of clutch retainer 109. Clutch retainer 109 is located internally within cage 111. In particular, cage 111 is the lowest part of assembly 101. Clutch assembly 107 is configured to nestle against a lower internal lip of cage 111 within a formed pocket of space. Clutch retainer 109 is in threaded attachment with cage 111 and is located above clutch assembly 107. Therefore, clutch assembly 107 is pressed down onto the lower internal lip of cage 111 by the tightening of clutch retainer 109. FIGS. 3 and 4 more clearly illustrate the location of clutch retainer 109. In this embodiment, clutch retainer is clearly internally housed within cage 111 and is not subjected to direct contact with external objects in the well, such as a bumper. By avoiding direct contact with a bumper at the bottom of the well, the life of the clutch is preserved. Impact forces are absorbed by cage 111.

FIGS. 3 and 4 are used to illustrate assembly 101 combined and in operation with stem 105 oriented between two different positions. As noted previously, when assembly 101 is traveling down through a well, stem 105 is naturally in a protruding position such that stem 105 is in a first position as seen in FIG. 4. The lower part of the head portion of stem 105 is resting on, or slightly above, clutch retainer 109. Hydrocarbons, liquids and contaminants within the well are passed through various channels or gaps within assembly 101, such as those formed in cage 111 to permit the passage of working fluid through internal chamber 115 of mandrel 103.

FIG. 3, in particular, illustrates stem 105 in the second position, wherein stem 105 is pressed against mandrel 103 by contact with an external member in the well. The transition to the second position occurs when assembly 101 impacts the bottom of the well. The impact seats stem 105 in the second position. The impact forces are absorbed predominantly through cage 111. In the second position, stem 105 is flush with the bottom surface of cage 111 and the upper surface of the head of stem 105 is pressed against a lower portion of mandrel 103. The contact between mandrel 103 and stem 105 forms a seal that cuts off the flow of fluid through mandrel 103. Note that the head of stem 105 in FIG. 3 is above that of various ports 113 located in the side of cage 111. The sealing effect prevents the passage of fluid through internal chamber 115 and results in a pressure gradient between the liquid above assembly 101 and that of the fluid below assembly 101. The pressure gradient causes assembly 101 to rise to the surface of the well and simultaneously remove the liquids and contaminants above it.

Stem 105 is illustrated as a cylindrical member having a head portion at an upper end. The shape and size of stem 105 is adapted to fit the sizing of assembly 101. Some embodiments may utilize various types of surface treatments along the main shaft of stem 105, such as threads or axial grooves to assist in the passing of solids across the clutch, however in the preferred embodiment, the main shaft of stem 105 is slightly textured as opposed to being relatively smooth.

Referring now also to FIGS. 5-8 in the drawings, clutch assembly 107 is illustrated. Clutch assembly 107 includes a clutch 117 illustrated in FIG. 5, a band 118 as seen in FIGS. 6A and 6B, and a ring 117 shown in FIG. 7. Clutch 117 is configured to engage the outer surface of stem 105 around the elongated shaft. Clutch 117 is a multi-member clutch wherein clutch 117 is partitioned into a plurality of radial portions. The portions are equally sized and spaced to permit equal surface contact with stem 105. Together, the members of clutch 117 surround and contact the circumference of stem 105. Clutch 117 is configured to permit a greater area of contact with stem 105 for a better transitioning as stem 105 transitions between the first and second positions. Although clutch 117 is shown having three members, it is contemplated that clutch 117 may include more or less members. Additionally, the members may be unequally sized in other embodiments as desired.

The respective positioning and orientation of the members of clutch 117 are held together through one or more retainers. The retainers are used to maintain the alignment and orientation of clutch 117. As seen in FIG. 7, clutch assembly includes ring 119. Ring 119 is configured to clip around a portion of clutch 117 to restrict the ability of each member of clutch 117 from separating from one another. Clutch 117 includes an upper and lower recessed groove 114 located around the circumference of the external surface of each member of clutch 117. Ring 119 is configured to rest within groove 114. Ring 119 is configured to protrude away from the outer surface 120 of clutch 117. The protruding rings 119 help to maintain the alignment of clutch 117 relative to cage 111. Rings 119 may contact internal surfaces of the cage within the seat which clutch 117 resides. It is understood that ring 119 is not limited to the specific depictions of FIG. 7. Ring 119 may be formed as a complete circle, without a gap, in other embodiments. The groove depth for rings 119 can be cut deeper or shallower on the exterior of clutch 117 to control external pressure applied to stem 105. The depth of the grooves regulates the external pressure on stem 105. Regulation of external pressures on stem 105 may also be accomplished through the use of different types of rings 119.

In FIGS. 6A and 6B, bands 118 are illustrated. Bands 118 are configured to wrap around a central body of the clutch members between grooves 114. An example of bands 118 are Hoopster bands. Bands 118 are bound between rings 119 so as to restrict the ability of bands 118 from sliding off clutch 117. Bands 118 are configured to provide additional strength and resistance to undesired movement of the members of clutch 117. In this way, bands 118 are configured to also maintain the alignment and orientation of the individual members of clutch 117. One or more bands 118 may be used depending on the size of each band. A slot 116 is maintained in each band to ensure appropriate flexure of band 118 and may also allow band 118 to possibly expand sufficiently to pass over the body of clutch 117 if rings 119 are engaged. FIG. 8 illustrates a side view of clutch 117 with phantom lines representing interior edges.

As mentioned previously, it is desired to regulate external pressures on stem 105. To accomplish this, clutch 117 may be configured to be a variable pressure clutch system through the use of different types of bands 118 and rings 119. The rings and bands of clutch 117 may be constant section rings, low load unobtrusive bands, and even elastomeric bands that fit on the outer parts of clutch 117 between the grooves. One or more dissimilar styles may be used simultaneously. Clutch 117 may optionally include an elastomeric band layered over bands 118 and/or ring 119. The mixing and matching of different bands 118 and rings 119 in one or more layers selectively allows for clutch 117 to accommodate and regulate varied external pressures on stem 105.

Referring now also to FIGS. 9 and 10 in the drawings, clutch retainer 109 is illustrated. Retainer 109 is configured to be located and secured within cage 111. Retainer 109 is located and seated above clutch assembly 107. Retainer 109 may be secured in various different ways. As depicted in the Figures, threaded engagement is one such method. This allows for the removal of retainer 109. Another method is to a pin that passes through a portion of cage 111 and retainer 109 that is also spot welded to cage 111 to prevent undesired removal. The weld prevents the backing out of the pin. When using a pin, retainer 109 would be torqued down to the desired level and then a hole would be drilled through cage 111 and into a portion of retainer 109. The spot weld would be done after inserting the pin into the hole and ensuring it passes through into retainer 109. Stem 105 is configured to pass through a central portion 124 of retainer 109. It is noted that retainer 109 is internally located within cage 111 and is protected from direct impact from the falling of plunger assembly 101 in the well. If in the event of failure of assembly 101, the internally mounted retainer 109 and clutch assembly 107 remain within cage 111 and are prevented from falling out into the well. This prevents the need to fish the parts out of the well.

Referring now also to FIGS. 11-13 in the drawings, cage 111 is further illustrated. Cage 111 is shown in a perspective view (see FIG. 11) and in a side section view (see FIG. 12). Threaded locations are seen for attachment of cage 111 to mandrel 103 at an upper portion, and a threaded location at a lower portion for attachment with retainer 109. Cage 111 is a one piece member and is configured to retain thicker walls so as to absorb the impact forces at the bottom of the well without incurring damage. Cage 111 has a gradual taper from an upper end, in communication with the mandrel, that slowly narrows down to a lower end opposite the upper end. The taper is configured to maintain a linear reduction in surface area from the upper end to the lower end of cage 111. This linear reduction permits for an increased thickness to assist in absorbing impact forces at the bottom of the well.

As noted previously, working fluid is configured to enter cage 111 through ports 113 and pass through internal chamber 115. As working fluid passes between the walls of the well and assembly 101, particulates may build up resulting in some restriction in flow through ports 113. Cage 111 is configured to include one or more flow cuts 121 formed into an outer surface of cage 111. Ports or slots 113 are located on flats or flow cuts 121. The object and purpose of the ports 113 and flow cuts 121 are to permit for the increased flow of liquid through internal chamber 115. Importantly, the liquid within the well may include contaminants that can build up and have differing sized dimensions. The use of flow cuts 121 can provide a larger area for the passage of contaminants. This reduces the chances of having to fish out the plunger from the well due to failed operations of the stem in not sealing. The ports 113 and flow cuts 121 are possible because of the thickened walls of cage 111. The thicker walls also help with absorbing impact forces as noted above. It is understood that one or more ports 113 and or flow cuts 121 are possible.

Flow cuts 121 are reduced thickness areas in the wall of the cage. As seen in greater detail in FIG. 13, exemplary designs of flow cuts 121 are illustrated and contemplated for use with assembly 101. Flow cuts 121 are equally spaced around the circumference of cage 111. Flow cuts 121 are configured to increase the distance between cage 111 with ports 113 and that of the walls of the well so as to minimize chances of restrictions and to increase flow of working fluid through ports 113. Although flow cuts 121 are illustrated as flat surfaces, it is understood that the contour may be modified to include one or more radiused surfaces.

The current assembly has many advantages over the prior art including at least the following: 1) three-piece clutch for added contact points with the stem; 2) an internally located clutch and clutch retainer within the cage; 3) inclusion of thicker walls within the cage; 4) inclusion of flow cuts in the outer surface of the cage; 5) Variable pressure clutch assembly; and 6) multiple bands used around the clutch.

The particular embodiments disclosed above are illustrative only, as the application may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. It is therefore evident that the particular embodiments disclosed above may be altered or modified, and all such variations are considered within the scope and spirit of the application. Accordingly, the protection sought herein is as set forth in the description. It is apparent that an application with significant advantages has been described and illustrated. Although the present application is shown in a limited number of forms, it is not limited to just these forms, but is amenable to various changes and modifications without departing from the spirit thereof. 

What is claimed is:
 1. A plunger assembly for use in a well, comprising: a mandrel; a cage coupled to the mandrel, the cage and the mandrel forming a body; an internal stem configured to translate within the cage and outside of the mandrel, the stem configured to selectively regulate the flow of fluid through the mandrel; and an internal clutch assembly coupled internally within the cage, the internal clutch assembly including a clutch configured to engage the stem.
 2. The plunger assembly of claim 1, wherein the clutch is partitioned into a plurality of equally sized radial portions.
 3. The plunger assembly of claim 1, wherein the clutch includes at least three radial portions.
 4. The plunger assembly of claim 3, wherein the three radial portions are equally sized.
 5. The plunger assembly of claim 1, wherein the clutch includes a groove configured to accept a ring, the ring configured to maintain the alignment and orientation of the clutch.
 6. The plunger assembly of claim 1, further comprising: a ring configured to maintain the alignment and orientation of a clutch within the internal clutch assembly, the ring housed within a groove in the clutch.
 7. The plunger assembly of claim 1, wherein the internal clutch assembly further includes a band configured to wrap around a central body of the clutch, the band being configured to hold the clutch together.
 8. The plunger assembly of claim 7, wherein the band is retained around the body of the clutch and restricted from sliding off the central body of the clutch.
 9. The plunger assembly of claim 7, wherein the internal clutch assembly uses one or more dissimilar bands.
 10. The plunger assembly of claim 9, wherein the bands of the internal clutch assembly are layered to vary the pressure applied to the stem.
 11. The plunger assembly of claim 7, wherein the band may be at least one of a low load unobtrusive band and an elastomeric bands.
 12. The plunger assembly of claim 1, wherein the cage is configured to gradually taper from an upper end in communication with the mandrel to a lower end opposite the upper end, the taper configured to maintain a linear reduction in surface area, the linear reduction permits for an increased thickness to assist in absorbing impact forces at the bottom of the well.
 13. The plunger assembly of claim 1, wherein the cage includes one or more flow cuts formed into the outer surface of the cage, the flow cuts being reduced thickness areas in the wall of the cage.
 14. The plunger assembly of claim 13, wherein the flow cut is configured to reduce the distance between a portion of the cage and an internal surface of the well so as to permit for the increased flow of fluid into the mandrel.
 15. The plunger assembly of claim 14, wherein the cage includes at least two flow cuts.
 16. The plunger assembly of claim 14, wherein the flow cuts are equally spaced radially around the cage.
 17. The plunger assembly of claim 1, wherein the cage includes one or more ports in the wall of the cage and configured to permit the passage of fluid into the mandrel.
 18. The plunger assembly of claim 17, wherein the one or more ports are located in a flow cut of the cage, the flow cut being a reduced thickness portion of the cage.
 19. The plunger assembly of claim 1, wherein the internal clutch assembly is configured to control external pressures applied to the internal stem. 